Endodontic therapy generally involves removal of the pulp of a tooth to eliminate an active infection, and the filling of the root canal space created by the endodontic therapy to prevent future infection. Endodontic therapy failure is generally due to persistent infection within the root canal space where bacteria form biofilms of microbial communities that adhere to dentinal tubules, root canal walls or external apical surfaces or a combination of these. In many cases, these persistent infections originate by re-colonization of bacteria through coronal leakage. The root canal environment, especially in areas difficult to reach by mechanical cleaning, provides a variety of conditions which favor the formation of biofilms, such as for example the presence of moisture, suitable attachment surfaces and nutrient sources from exudates of the periapical tissues. Bacterial biofilm communities are encased in an extracellular polymeric matrix that makes biofilms inherently resistant to antibacterial agents due to physical diffusion barriers and physiological differences between the biofilm communities and the host. For example, a recent in vitro study showed that wild-strain bacteria of endodontic origin grown over 8 days on dentin slices of extracted teeth generate biofilms that were resistant to eradication by ampicillin, azithromycin, clindamycin, doxycycline and metronidazole.
Therefore, several strategies have been used to decrease the formation of biofilms to levels below a threshold of interference with endodontic therapy. One strategy has been to increase the physical removal of bacteria during endodontic therapy. Other strategies have been to inhibit the growth of bacteria and to reduce secondary colonization of the root canal, including treating surfaces with different repelling substances, incorporating antimicrobial products into surface materials, coating surfaces with antimicrobials, and by modifying the physicochemical properties of the surfaces to make the surfaces less favorable to biofilm formation. Thus far, however, these techniques have not been sufficiently successful to prevent or control the formation of biofilms in root canals.
Therefore, there is a need for a method for reducing bacterial biofilm formation after endodontic therapy.